Tetrapod

Clade of the first four-limbed vertebrates and their descendants

A tetrapod (from Ancient Greek τετρα (tetra) 'four' and πούς (poús) 'foot') is any vertebrate animal of the clade Tetrapoda. The main diagnostic and defining trait (synapomorphy) of tetrapods is having four limbs, connected to the shoulder- and pelvic girdles, for which the group is named. As a clade, Tetrapoda is defined such that it includes every organism which descended from four-limbed ancestors, including those which have lost some or all of these limbs, e.g.

From Wikipedia, under CC BY-SA. More on occurri.